Enclosures for vacuum coating

ABSTRACT

A vacuum enclosure for use in vacuum deposition, having an internal workholder to support the article being treated, and a hinged semi-cylindrical side door which can be swung open to give access to the interior and will seal against the main wall of the enclosure, and against the top and base plates. The main enclosure is also semi-cylindrical thus defining a cylindrical space around the circular workholder. Where the edges of the side door and main enclosure meet, flanges are provided at an angle of preferably 30* from the tangent to the cylindrical enclosure and a sealing ring extends all the way around a door where it closes onto the enclosure and especially down the angled side edges.

O United States Patent [191 nu 3,892,198 Dobson July 1, 1975 [5 ENCLOSURES FOR VACUUM COATING Wiley & Sons, N.Y., (I962), TK7835-B3C2,Gpl60, [76] Inventor: Christopher David Dobson, 157

Linden Ct., Newbridge, Monmouthshire, England Primary ExaminerMorris Kaplan [221 Filed; June 27, 1974 Attorney, Agent, or Firm-P0ll0ck, Philpitt & Vande Sande [2i] Appl. No.: 483,501

[52] US. Cl. 118/49 [57] ABSTRACT [51] Int. Cl. C23c 13/08 [581 Field of Search 118/48-50]; A vacuum enclosure for use vacuum depflsltwn, 7 19, 364072, 4 34/92; having an internal workholder to support the article 3 5 7 9; 2 47 5 3 7; being treated, and a hinged semi-cylindrical side door 2 5 2 R 28 3 z gl 96 which can be swung open to give access to the interior and will seal against the main wall of the enclosure, 5 References Cited and against the top and base plates. The main enclo- UNITED STATES PATENTS sure is also semi-cylindrical thus defining a cylindrical I space around the circular workholder. Where the $23 11 edges of the side door and main enclosure meet, 2:343:S86 3/1944 Cornell, 11,111... .fiss/ls B ux flanges are prov'ded an .angle of preferably 'f 2,852.4 M958 McNary ct alm H 8/49 x the tangent to the cylindrical enclosure and a sealing 1473.954 "H1969 Manson l I I I I H 1 13/48 X ring extends all the way around a door where it closes 3,526,206 9/1970 Jones Its/49.1 onto the enclosure and especially down the angled 3,590,776 7/l97l Tudor ll8/50.l X side edges.

OTHER PUBLICATIONS Bakish, Introduction to Electron Beam Technology,

5 Claims, 6 Drawing Figures g 9 3s :U CL 17 1a 16 ENCLOSURES FOR VACUUM COATING This invention relates to vacuum enclosures for use in high vacuum coating techniques, as used for example in the production of semi-conductors, and also certain optical products, and also for example in the application of thin metal layers on to glass or synthetic plastic products.

Conventional vacuum enclosures for such processes comprise a glass belljar arranged to fit on and be sealed to a base plate by a rubber sealing ring. The base plate may have a number of apertures or fittings to accommodate the various services required within the enclosure, such as low and high voltage supplies. mechanical drives, and couplings for gas supply ducts. It is also known to use bell jars fabricated from other materials which can be water cooled and thus able to operate at higher temperatures. Bell jar type enclosures have two main disadvantages owing to the fact that the jar normally has to be raised vertically off the work pieces and all the ancillary equipment mounted on the base plate; firstly it is necessary to provide a hoist to raise the jar, and also accurate guides to avoid damaging the work pieces, and secondly the use ofa hoist requires considerable overhead clearance which can be very inconvenient.

Accordingly it is an object of the invention to provide an improved vacuum enclosure which will avoid at least some of the disadvantages of conventional bell jar type enclosures which have to be lifted off the internal structure or mechanism of the vacuum treatment equipment, but which will enable adequate access to the internal structure, whilst ensuring that good vacuum seals are formed during the evacuation step of the process.

In accordance with this object, the invention provides a cylindrical vacuum enclosure for vacuum coating processes comprising a main body portion of partcylindrical form including part of the side wall of the cylindrical enclosure which is shaped to define a lateral opening extending around substantially 180 of the periphery of the cylindrical enclosure, said enclosure including top and bottom circular plates, said bottom plate defining apertures to accommodate electrical, mechanical or other inputs to the enclosure, said top and bottom plates connected to said main body portion with an air-tight seal, a workholder within said enclosure arranged to support devices for coating, and means for supporting and rotating said workholder, a movable access closure member of approximately semi-cylindrical shape arranged to form a seal with the body portion around said lateral opening, mutually cooperating vertical flanges being provided between said body portion at the two sides of the lateral opening and at the two sides of the closure member, the mutually cooperating flanges being provided at an angle of from to 60 from the tangent to the side wall of the cylindrical enclosure and to the closure member respectively, a hinge for the closure member provided between one pair of said mutually cooperating flanges on one said side, and a locking flange on the other pair of flanges for retaining the closure member in sealing relationship to the peripheral walls of the opening in the body portion, and a sealing ring between the cooperating surfaces of the closure member and the peripheral walls of the opening in the main body.

It will be understood that the term vacuum enclosure" as used herein does not necessarily imply that the enclosure is complete: it may be designed to combine with another element to form the actual vacuum vessel, as for example a bell jar combines with a base plate to form the complete sealed chamber.

By forming the whole enclosure as a cylindrical shape this minimises the wasted internal volume, and maximum accessibility, effective sealing, and minimum wasted volume are achieved by forming the closure member in the semi-cylindrical shape.

Ideally the edges of the door and the enclosure, where they meet, are provided at an angle from the tangent at the meeting point of no greater than 45 and the specifically preferred angle is 30. If such an angled arrangement was not provided, but the door was allowed to meet the enclosure by overlapping, any seal present between the overlapping portions would be subjected to a sliding motion which would probably result in dislodging of the seal from the groove in which it sits. Conversely if the meeting surfaces where the seal is provided are formed in a radial direction of the enclosure it is possible that the seal may not be made in a positive manner. I have discovered that by forming the surfaces at an angle, as in the claimed invention, the seal is subjected to a slight sliding action which is initially effective to press the seal into a lozenge shape so that good sealing contact between the two surfaces is achieved. Because of the angle, however, the sliding movement during closing is only for a short distance and thus the seal is not sufficiently deformed to cause the seal to be torn out of the groove in which it sits. By this arrangement a very positive seal is achieved upon closure of the door and this is even further enhanced if the sealing ring is of hollow cross-section.

Both the body portion and the closure member may be formed of metal, for example stainless steel, which minimises contamination within the vacuum chamber.

The invention may be performed in various ways and one particular embodiment will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partly cut-away general perspective view of a vacuum enclosure according to the invention with the access door open,

FIG. 2 is a rear view of the enclosure with the door closed,

H6. 3 is a horizontal cross-section on line ll] III of FIG. 2 showing the door sealing arrangement,

FIG. 3A is a detail of FIG. 3 illustrating a modified sealing ring,

FIG. 4 is a perspective view of interengaging parts of the door sealing arrangement, and

FIG. 5 is a partly cut-away view of part of one of the sealing members showing the sealing ring retaining groove.

in this example the enclosure comprises a main body having a circular domed top plate 10 and a fixed semicylindrical side wall 11 extending into a lower cylindrical part 12, which rests on a bottom plate 13. This bottom plate 13 is provided with a main opening 14 for connection to a high vacuum difi'usion pump system (not shown), in the normal manner. The bottom plate is also provided with sealed couplings or connections for electrical, mechanical, gaseous and other inputs and/or outputs, and supports for appropriate furniture", i.e. equipment for supporting workpieces within the vacuum chamber and the equipment for evaporating the substance used for coating. In this particular example the base plate is provided with three support posts carrying a horizontal support ring 16 at their upper ends and on this ring is mounted a further rotary ring 17 located by bearings 18 and having a dome 19 with apertures 20 in which small circular discs or other workpieces can be located. The ring 17 and the dome can be rotated about a vertical axis by a friction wheel 21 driven through a small bevel gearbox from a vertical drive shaft 22 whose lower end passes through a sealed rotary coupling 23 in the base plate. The coupling 23 has a connection below the base plate for attachment to an external rotary drive whereby the dome 19 can be slowly turned during the coating process and while the chamber is subject to vacuum. The metal to be evaporated is contained in a small heated bowl or boat (not shown) supported centrally below the dome 19 and connected to an external electrical heater supply through a pair of electrical insulated terminals such as 24, 25 mounted in the base plate 13. The base plate is also formed with other electrical, mechanical, and/or gas couplings or inputs as indicated diagrammatically for example at 26, which may be used for different arrangements of furniture for various different vacuum coating processes. The top plate 10 is likewise provided with sealed input/output couplings indicated at 26A.

The top plate 10 is welded and sealed in a gas-tight manner to a ring 27 which carries, by a gas-tight joint, the half-cylindrical side wall 11, and this wall is provided with vertical flanges 28 at opposite sides lying on a common diametral plane. The enclosure is completed by a half-cylindrical hinged door 29 hinged to the body on a pair of hinges 30 adjacent one of the vertical flanges 28. This door also has vertical flanges 31 along both opposite sides to co-operate with the flanges 28 on the body, and a rubber ring 32 of circular cross-section is located in a groove 33 in the internal edge surfaces of the hinged door to seal against the corresponding surfaces of the top ring 27 and a bottom ring 34 and the vertical flanges 28 of the body part when the door is closed.

As can be seen from FIGS. 3 to 5 in particular, the co-operating flanges 28 and 31, on the wall 11 and the door 29 respectively, are set at an angle; in this case 30 to the tangent to the cylindrical walls of the wall 11 and door 29. Thus. when the door is shut, at the final stage of closing, the angled faces of the flanges 28 and 31 will be subjected to a slight sliding action which will be effective to press the sealing ring 32 into a lozenge shape, but the forces on the ring 32 will not be so great as to cause disruption of the ring from its groove 33. It will be seen incidentally that the groove 33 is so formed that the walls thereof converge towards one another in the direction towards the groove opening so that the ring is held tightly in the groove. lt will be appreciated also that a similar sliding-seal action is produced on the sealing ring 32 against the top and bottom rings 27 and 34 as the door 29 closes. Thus a very secure sealing effect is achieved in the region of the flanges 28 and 31 when the door is fully closed to ensure that an adequate sealing may be achieved as is necessary with vacuum chambers.

In use the articles to be treated are inserted in the chamber, and the door 29 is closed, sealed, and located by a catch 35 engaging a fitting 36 on the door. The aperture 14 in the bottom plate is connected in the normal manner to a vacuum pumping system (not shown) for evacuating the chamber and the process of vacuum deposition is then carried out.

It will be appreciated that this enclosure gives a minimum of internal wasted volume when used with circular swept-volume equipment, and a minimum of internal surface area on which contaminents could collect, and also avoids the disadvantages of a bell jar system, while providing excellent accessibility to the internal structure.

The door 29 and side wall 11 may be formed of stainless steel sheet, and provided with a viewing window 37. ln some examples of the invention the door is formed wholly or partly of a rigid transparent material such as glass which allows inspection of the interior but will not have any harmful effect on the vacuum conditions inside the enclosure. The enclosure is separable from the bottom plate 13, so that it provides in effect a form of bell jar with a hinged side door. Thus the enclosure includes a bottom ring 38 to which the fixed cylindrical part 12 is attached and also a complete annular sealing ring 39 in a groove in the base of the ring 38 to rest on and provide an effective seal with the base plate 13.

The angles produced by the flanges 28 and 31 are preferably 30 but good results can be obtained if the angle is no less than 15 and no greater than 45' although an angle of up to 60 is possible.

The hollow sealing ring 32A shown in FIG. 3A provides a particularly effective seal.

I claim:

1. A cylindrical vacuum enclosure for vacuum coating processes comprising a main body portion of partcylindrical form including part of the side wall of the cylindrical enclosure which is shaped to define a lateral opening extending around substantially of the periphery of the cylindrical enclosure, said enclosure including top and bottom circular plates, said bottom plate defining apertures to accommodate electrical, mechanical or other inputs to the enclosure, said top and bottom plates connected to said main body portion with an air-tight seal, a workholder within said enclosure arranged to support devices for coating, and means for supporting and rotating said workholder, a movable access closure member of approximately semi-cylindrical shape arranged to form a seal with the body portion around said lateral opening, mutually cooperating vertical flanges being provided between said body portion at the two sides of the lateral opening and at the two sides of the closure member, the mutually cooperating flanges being provided at an angle of from 15 to 60 from the tangent to the side wall of the cylindrical enclosure and to the closure member respectively, a hinge for the closure member provided between one pair of said mutually cooperating flanges on one said side, and a locking flange on the other pair of flanges for retaining the closure member in sealing relationship to the peripheral walls of the opening in the body portion, and a sealing ring between the cooperating surfaces of the closure member and the peripheral walls of the opening in the main body.

2. A cylindrical vacuum enclosure according to claim 1, wherein the angle of the co-operating flanges is no greater than 45.

3. A cylindrical vacuum enclosure according to claim 1, wherein the angle of the co-operating flanges is 30.

ceipt of the sealing ring, the walls of the groove converging towards each other to the outside of the groove. 

1. A cylindrical vacuum enclosure for vacuum coating processes comprising a main body portion of part-cylindrical form including part of the side wall of the cylindrical enclosure which is shaped to define a lateral opening extending around substantially 180* of the periphery of the cylindrical enclosure, said enclosure including top and bottom circular plates, said bottom plate defining apertures to accommodate electrical, mechanical or other inputs to the enclosure, said top and bottom plates connected to said main body portion with an air-tight seal, a workholder within said enclosure arranged to support devices for coating, and means for supporting and rotating said workholder, a movable access closure member of approximately semi-cylindrical shape arranged to form a seal with the body portion around said lateral opening, mutually cooperating vertical flanges being provided between said body portion at the two sides of the lateral opening and at the two sides of the closure member, the mutually cooperating flanges being provided at an angle of from 15* to 60* from the tangent to the side wall of the cylindrical enclosure and to the closure member respectively, a hinge for the closure member provided between one pair of said mutually cooperating flanges on one said side, and a locking flange on the other pair of flanges for retaining the closure member in sealing relationship to the peripheral walls of the opening in the body portion, and a sealing ring between the cooperating surfaces of the closure member and the peripheral walls of the opening in the main body.
 2. A cylindrical vacuum enclosure according to claim 1, wherein the angle of the co-operating flanges is no greater than 45*.
 3. A cylindrical vacuum enclosure according to claim 1, wherein the angle of the co-operating flanges is 30*.
 4. A cylindrical vacuum enclosure according to claim 1, wherein the sealing ring defines a hollow cross-sectional shape.
 5. A cylindrical vacuum enclosure according to claim 1, wherein the closure member defines a groove for receipt of the sealing ring, the walls of the groove converging towards each other to the outside of the groove. 